Yanmar 2GM20F Heat exchanger refurbishable?

D

Dubo

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Oct 26, 2010
84
Hunter 340 Deltaville Va
I removed the heat exchanger from a Yanmar 2GM20F and would like to replace the shroud surrounding the core. Does anyone if that is doable and if so, how are the brass end caps which the tubes pass through removed? Did Yanmar pressure fit them on or will a little PB blaster and firm tapping with a wooden mallet do the job? The shroud is pitted and I'd like to avoid spending 600.00 for a new HE if what I have is salvageable. Also, does anyone know of anyone who salvages these parts for resale?
Thanks!
 
kloudie1

kloudie1

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Nov 6, 2006
9,898
Hunter 34 Mandeville Louisiana
Some observations.. The shroud being pitted would not be a real worry. It is in coolant and there is minimal pressure differential across it; keep the coolant fresh and there should no further pitting. If the pits have pierced the shroud, they can be soldered , but the hole would have to be pretty big (1/4" or so) before it would start affecting the heat exchanger.
The tubes are probably rolled (expanded by roller) into the end plates (technically "tube sheets" ) so ya not going to get them out without destroying the tubes. I could be wrong on that one, but rolling would be the normal way that joint would be made for mechanical strength and tightness.
If the tubes are in really bad shape when inspecting the inside, ya might want to get a new tube bundle assembly.. otherwise, solder the shroud pits if they make ya nervous..
 
Allan12210

Allan12210

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Jan 22, 2008
1,654
Hunter 34 Alameda CA
kloudie1 said:
The tubes are probably rolled (expanded by roller) into the end plates
Click to expand
Swaged by inserting a mandrel? Non removable as Claude says.

Once my friend took his HE to a radiator shop and they boiled it for way too long. The shroud in his case was an aluminum sleeve with a couple of large holes (one near each end). The entire sleeve completely disappeared. We figured out that the solution was too alkaline and the guy must have gone out for a beer. Yours might have been cooked once in its lifetime, hence pitting. The sleeve is put on before the last end plate and the tubes are expanded. If its like my friend's, it doesn't slide off. In fact the end plates are machined so the sleeve is even with their diameter. Maybe yours is different? Anyway, we found a piece of aluminum tube the right inner diameter. After chucking it in a lathe we machined off enough of the outside that it would fit back into the tank when installed. Then we drilled the correct holes and slit it completely down its length. That allowed us to expand it enough to slide it back over one end. A machine shop TIG welded the slit back together. And that's all it takes to change it.

I agree with Claude. If it's still working, wait until it really breaks. With proper coolant, its still going to last a long time.
 
Mark Maulden

Mark Maulden

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Jan 25, 2011
2,403
S2 11.0A Anacortes, WA
Im not a Yanmar guy, but doesnt the "20" in the engine model mean 20 hp? If so, the exchanger cant be that big. Before spending a bunch of money for machine work etc, think about a new exchanger custom made or direct replacement. Just not from Yanmar. I broke mine today (dont ask) and being a 36 hp Volvo, their price is around $1500.00...However, there are three companies in Bellingham WA (1/2 hr drive) that make exchangers and make them as OEM. Good chance one of them made yours. I called two of them and they quoted me around 325.00 for a new custom exchanger built how I want it. The third was $600. In a way I'm sorta glad it happened as Ive always wanted to get this HX off the engine mounted somewhere else. Piss poor design..They're not as expensive as one might think...The three are Seakamp Engineering with a website, SanJuan Engineering with no website that i could find but with some searching, can find a phone #, and Orca Engineering with a website. Seakamp and San Juan gave me the $325 numbers while Orca gave me around $600.. All i asked for were ballpark numbers and San Juan actually spent the time discussing my problem.
 
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